What was found
SYS B HYD SYS FAILED INFLT B HYD INDICATED ZERO GAL & PRESSURE BEGAN TO DECREASE BELOW 200 PSI. EVALUATION SHOWS LEAK FROM UPPER RUDDER AREA. F/E NOTED DECREASING "B" SYS QTY & MONITORED QTY & PRESSURE. AS PRESSURE DECREASED, AS SOON AS NR 2 "B" PUMP LOW PRESSURE LIGHT STARTED TO FLICKER, TURNED OFF BOTH "B" PUMPS. NO LOW PRESSURE LIGHT NOTED ON NR 1 "B" PUMP. CAUSE LIKELY UPPER RUDDER ACTUATOR FAILURE. REMOVED RUDDER POWER UNIT IAW AMM 27-20-141-2. INSTALLED NEW POWER UNIT REF AMM 27-20-141-2. PERFORMED LEAK CHECK WITH ALL 3 ENGS, RUDDER FULL DEFLECTION IN BOTH DIRECTIONS, NO LEAKS NOTED. ACCOMPLISHED ADJUSTMENT AND TEST IAW AMM 27-20-141-2. OPS CK NORMAL.